A half-century ago, the Space Race was fought between nations. Today, that battle has a decidedly scrappier feel, with start-ups leading the charge.

One recent entrant is the Golden Spike Company, a Boulder-based start-up that plans to offer human expeditions to the moon. Earlier this month, the company announced that it would begin shuttling manned crews to the moon by 2020. There's only one small catch: The price of admission is about $1.4 billion for two passengers.

Unlike more consumer-focused space exploration missions, like Richard Branson's Virgin Galactic--which will take passengers into sub-orbital spaceflight for $200,000--Golden Spike's founder says its company's clientele will be comprised mainly of governments and corporations.

"We can give countries an expedition to surface of the moon for two people," Alan Stern, the co-founder of Golden Spike and NASA's former chief scientists told Wired

Stern believes that firms already operating within the private spaceflight industry have created the basic technology that makes commercialized space travel a possibility. Now, according to the company mission, "Golden Spike will exploit these advances, and others in the late stages of development, for commercial use, to offer human expeditions to the Moon at prices comparable to robotic flagship missions."

Though the start-up has declined to offer information about its financing, its team of scientists, venture capitalists, and politicians is impressive. Among those listed on its board includes Esther Dyson, the NewSpace investor and venture capitalist, Jeff Ashby, a former NASA space Shuttle commander, and Newt Gingrich, former U.S. Speaker of the House.

Golden Spike is hardly the first start-up in the last several years to make space travel and a lunar landing its mission.

Planetary Resources, a Seattle-based start-up founded by former Google executives, formed in 2010 to "expand Earth's natural resource base." The company's mission is straight from a sci-fi playbook: they are developing tools to mine asteroids.

Moon Express, commonly refereed to as MoonEx, formed in 2010, and plans to send missions to the moon by 2015. The company, based out of NASA's research lab in Mountain View, California is led by Naveen Jain, Barney Pell, and Robert D. Richards. The founders and its 15 employees are gunning to win Google's $20 million Lunar X Prize, which will be awarded to the first company to safely reach the moon.

But the most entrenched start-up in the space travel industry is perhaps SpaceX, a company formed in 2002 by Elon Musk, the PayPal co-founder and creator of the Tesla Motors. For the last decade, SpaceX has been developing commercially viable rockets to launch customers into space. This week, the company successfully tested its Grasshopper rocket, which rose to 131 feet, hovered, and safely landed.

Why do entrepreneurs seem so suddenly enthralled by the prospect--and potential value--of space exploration? According to Alan Stern, it comes down to one basic economic principle: there will be a huge market for it.

"We're not just about America going back to the moon; we're about American industry and American entrepreneurial spirit leading the rest of the world to an exciting era of human lunar exploration," Stern said in a statement. "It's the 21st century, we're here to help countries, companies, and individuals extend their reach in space, and we think we'll see an enthusiastic customer manifest developing."